Renewable resins and thermoplastics from eugenol

ABSTRACT

An eugenol, an abundant natural phenol and the primary component of clove oil, which is converted to a thermoset resin via a high yield, two-step reaction. Modest heating yields a thermoset material with thermal stability above 350° C., a glass transition temperature of 187° C. and water uptake of only 1.8%.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention described herein may be manufactured and used by or forthe government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

FIELD OF THE INVENTION

The invention generally relates to eugenol, an abundant natural phenoland the primary component of essential oils (clove oil), which isconverted to a thermoset resin via a high yield, two-step reaction.Modest heating yields a thermoset material with thermal stability above350° C., a glass transition temperature of 187° C. and water uptake ofonly 1.8%. Eugenol can be converted to a variety of thermosetting resinsincluding epoxies, and cyanate esters. Eugenol can also be converted tothermoplastics including polycarbonates, polyether ether ketone (PEEK)and polysulfones.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the DSC trace of the cyanate ester, accordingto embodiments of the invention.

FIG. 2 is a graph showing the IR spectra for the cyanate ester resin andcured thermoset, according to embodiments of the invention.

FIG. 3 is a graph showing the TMA data illustrating the glass transitiontemperature of the cyanate ester thermoset, according to embodiments ofthe invention.

FIG. 4 is a graph showing the TGA data for the fully cured cyanate esterresin, according to embodiments of the invention.

FIG. 5 is a graph showing the comparison of IR spectra of eugenol andthe gaseous decomposition products derived from the cured cyanate esterat 416° C., according to embodiments of the invention.

FIG. 6 is a chemical schematic showing X-ray crystal structures of thesaturated bisphenol (top and analogous cyanate ester (bottom) derivedfrom eugenol, according to embodiments of the invention.

It is to be understood that the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not to be viewed as being restrictive of the invention, as claimed.Further advantages of this invention will be apparent after a review ofthe following detailed description of the disclosed embodiments, whichare illustrated schematically in the accompanying drawings and in theappended claims.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

The invention generally relates to eugenol, an abundant natural phenoland the primary component of essential oils (clove oil), which isconverted to a thermoset resin via a high yield, two-step reaction.Modest heating yields a thermoset material with thermal stability above350° C., a glass transition temperature of 187° C. and water uptake ofonly 1.8%. Eugenol can be converted to a variety of thermosetting resinsincluding, but not limited to: epoxy and cyanate ester resins. Eugenolcan also be converted to thermoplastics including, but not limited topolycarbonates, polyether ether ketones (PEEK), and polysulfones.

Naturally occurring phenols that can be readily derived from essentialoils or high volume components of biomass, such as lignin, arecompelling feedstocks for the generation of full performance resins andpolymers. In some cases the structural diversity of these phenols allowsfor powerful and efficient synthetic methods to be utilized withbenefits including selectivity, improved carbon efficiency, and uniqueelectronic and steric interactions. Eugenol, a phenol which comprisesapproximately 80% of clove oil embodies this class of renewable phenols.The terminal olefin provides a synthetic handle for polymerization andchemical modification, while the aliphatic chain and methoxy groupgreatly impact the physical properties of polymers derived from eugenol.

A variety of polymers have been prepared from eugenol based monomers.Polyacetylenes have been synthesized from a monomer generated byreaction of propargyl chloride with eugenol. (Rahim, E. A.; Sanda, F.;Masuda, T. J. Macromolec. Sci. Part A 2004, A41, 133-141; Rahim, E. A.;Sanda, F.; Masuda, T. J. Polym. Bull. 2004, 52, 93-100). Co-polymerscomprised of BPA polycarbonate and eugenol/siloxane blocks have alsobeen extensively studied. (Hagenaars, A. C.; Bailly, Ch.; Schneider, A.;Wolf, B. A. Polymer 2002, 43, 2663-2669) More recently, methacrylicderivatives of eugenol have been used as components of dental compositesand bone cements. (Rojo, L.; Vazquez, B.; Parra, J.; Bravo, A. L.; Deb,S.; San Roman, J. Biomacromolecules 2006, 7, 2751-2761)

An important consideration when developing synthetic methodology for thepreparation of molecules derived from renewable materials is the abilityto utilize efficient and selective catalysts. In cases where alkenes areavailable for reaction, olefin metathesis can be a powerful techniquefor selectively generating new carbon-carbon bonds. The self-metathesisof eugenol with 1st and 2nd generation Grubbs' catalysts has beendescribed, (Blackwell, H. E.; O'Leary, D. J.; Chatterjee, A. K.;Washenfelder, R. A.; Bussmann, D. A.; Grubbs, R. H. J. Am. Chem. Soc.2000, 122, 58-71; Runge, M. B.; Mwangi, M. T.; Bowden, N. B. J.Organomet. Chem. 2006, 691, 5278-5288) as have a number ofcross-metathesis reactions. As an extension of this chemistry, a varietyof bifunctional monomers containing eugenol moieties have been preparedwith various linkers including butyl, decyl, carbonate, or glycol. Thependant olefins could then be polymerized by self-metathesis (Giinther,S.; Lamprecht, P.; Luinstra, G. A. Macromol. Symp. 2010, 293,15-19).Despite the significant amount of work conducted on eugenol polymers,there are no reports on the use of the reduced self-metathesis productof eugenol, 4,4′-(butane-1,4-diyl)bis(2-methoxyphenol), as a precursorto thermoplastics or other resins such as cyanate esters. This bisphenolhas a number of advantages over common resin precursors such asbisphenol A given the low toxicity of eugenol and the relatively longaliphatic chain between phenols. The increased distance between phenolsis expected to decrease the activity of the molecule as an endocrinedisruptor. Moreover, the presence of ortho-methoxy groups may disrupthydrogen bonding interactions that are essential for efficient bondingof phenols to receptor active sites. Recently, a significant amount ofwork by our group has been conducted on cyanate esters derived fromrenewable phenols. Cyanate esters are of particular interest due totheir high glass transition temperatures, processability, low wateruptake, and excellent FST (Flame, Smoke and Toxicity) properties.Embodiments of the invention describe methods for the synthesis andcharacterization of thermosetting resins and thermoplastics from theabundant biofeedstock eugenol. The cure behavior of the resin and itsfundamental properties are then described.

The coupling ofeugenol via olefin metathesis was accomplished with the1^(st) generation Grubb's catalyst utilizing a modest, 1% catalystloading (Chemical Schematic 1). A variety of other olefin metathesiscatalysts based on and including, but not limited to, Ru, Mo, W, or Recan be used to facilitate this transformation. In embodiments thereaction is conducted without solvent. In embodiments the reaction isconducted in an organic solvent. Ethylene is generated as a byproduct ofthe reaction and in embodiments of the invention, ethylene can beremoved under reduced pressure or other means including active spargingwith an inert gas, or reflux under an inert gas. In other embodimentsthe ethylene is collected. Yields of the coupled alkene (93%) weresignificantly higher than that reported in the literature (71%), perhapsdue to the scale of the reaction or the work-up procedure which includeda base extraction of the phenol. (Blackwell, H. E.; O'Leary, D. J.;Chatterjee, A. K.; Washenfelder, R. A.; Bussmann, D. A.; Grubbs, R. H.J. Am. Chem. Soc. 2000, 122, 58-71). In embodiments, when a rutheniumbased catalyst is used for the metathesis reaction, the catalyst is alsoused as the hydrogenation catalyst to reduce the unsaturated bisphenol.In embodiments, an additional hydrogenation catalyst based on metalsincluding, but not limited to, Ni, Pd, Pt, Cu, or Ru is added to thereaction mixture to increase the rate of the subsequent hydrogenation.In embodiments the metathesis catalyst is heterogeneous and is removedby filtration and reused in subsequent preparations. The product couldbe effectively purified by base extraction followed by reprecipitation,while analytically pure material could be obtained by standardtechniques.

Chemical Schematic 1. Synthesis of a Cyanate Ester Resin and ThermosetNetwork from Eugenol

Synthesis of a cyanate ester from the bisphenol is straightforward.Although the bisphenol showed low solubility in ether solutions, amixture of ether and acetone effectively dissolved the bisphenol but wasnot an effective solvent for the product cyanate ester. This allowed forcollection of the crude product by filtration. Residual salts wereremoved with a water wash and the desired product was produced in highpurity and yield by recrystallization from ethyl acetate.

The ¹H and ¹³C NMR spectra of the compounds were consistent with theirstructures, but to further characterize the compounds, the singlecrystal X-ray structures of both the bisphenol and the cyanate esterwere determined (Chemical Schematic 2). The crystal packing of thebisphenol is affected by several hydrogen bonding interactions. Theseinteractions include an intramolecular hydrogen bond between thehydroxyl and methoxy groups with a distance of 2.22 Å. This stronghydrogen bonding interaction results in orientation of the hydroxylhydrogen toward the methoxy group. Three additional intermolecularhydrogen bonds of 2.29, 2.31, and 2.71 Å tie neighboring phenolstogether into a 3-dimensional lattice. As expected, the 4-carbon groupbetween aromatic rings is in the anti-configuration which results in thearomatic rings being nearly parallel with an inter-ring angle of lessthan one degree. No evidence was observed for non-classical bondinginteractions or I-stacking. The structure of the cyanate ester sharesmany of the structural features of the bisphenol. The sameanti-configuration is observed for the 4-carbon group between thearomatic rings, but the chain is disordered suggesting that anotherconformation is also present in the crystal lattice. The aromatic ringsare parallel with an inter-ring angle of zero degrees.

After the cyanate ester was fully characterized it became of interest toexamine the cure chemistry of the resin by DSC (FIG. 1). The resinexhibited a sharp melting point at 104° C. and a broad exotherm from182-325° C. This results in a processing window of nearly 80° C., whichallows for simplified fabrication of composite materials. The enthalpyof reaction was 201.2 kJ/mole or 100.6 kJ/mole (—OCN) which isconsistent with complete conversion of the cyanate esters to cyanuraterings. A standard cure protocol (150° C. for 1 h, 210° C. for 24 h) wasemployed to generate a fully cured resin puck for further analysis. Thedegree of cure was qualitatively evaluated by comparing the IR spectraof the starting cyanate ester and the cured resin (FIG. 2).Disappearance of the strong C—N stretch at 2253 cm⁻¹ along withappearance of the cyanurate ring bands at 1608 and 1364 cm⁻¹ confirmedthat the cyanate ester cured completely under the applied protocol. Inaddition, DSC analysis of the cured sample showed no residual exotherm(FIG. 1) providing further evidence that complete cure had beenachieved.

The glass transition temperature of the cured resin was measured by TMA.The T_(g) (tan δ) was 186° C. (FIG. 3) which is relatively low comparedto more rigid cyanate esters, but is competitive with high-temperatureepoxy-resins. Compared to conventional bis-cyanate esters that typicallyhave a more rigid one-carbon bridge between the aromatic rings, the4-carbon chain between the aromatic rings in compound 3 lowers the T_(g)of the thermoset. However, the structural flexibility of the aliphaticchain imparts unique properties to the resin. One of the key advantagesof cyanate esters over other thermoset resins is their relatively lowwater uptake and excellent stability to hydrolysis reactions.Particularly for maritime environments, these characteristics can bevital to long term performance. To evaluate the effect of water on theglass transition temperature and thermal stability of this resin, acured resin puck was immersed in 85° C. water for 96 hours. The wateruptake was only 1.8% which is substantially less than the completelycured cyanate ester derived from bisphenol A (BADCy) at nearly 3% andalso less than fully cured dicyanate esters derived from creosol. The“wet” T_(g) for this material was then determined by an additional TMAstudy and showed a decrease in T_(g) of only 19° C. Thus, the “wet”T_(g) indicates performance comparable to the dry T_(g)s of the highestperforming aerospace grade epoxy resins.

To further characterize the thermal stability of the cured resin, TGAexperiments were conducted in N₂ and air (FIG. 4). In N₂ the materialwas stable up to ˜350° C. with 5% weight loss at 360° C. and 10% weightloss at 374° C. The char yield (measured at 600° C.) was 31%. Thisnumber, although relatively low for cyanate ester thermosets, is notsurprising given the extra mass of thermally labile moieties includingthe methoxy and aliphatic bridging groups. A simple calculation basedonly on the number of aromatic carbons and assuming that the cyanuraterings decompose completely to cyanuric acid would give a theoreticalchar yield of only 41%. Based on this, the cyanate ester produces 75% ofthe expected char which is similar to the results from BADCy. When thethermal analysis is conducted in air, the material exhibits some uniquebehavior. From about 400-525° C. the char yield in air is actuallyhigher than in N₂, but the mass then rapidly decreases to zero at 600°C., suggesting that a partial oxidation reaction at ˜400° C. increasesthe mass of the residue but then renders the material unstable at highertemperatures. FIG. 4. TGA data for the fully cured cyanate ester resin.

FIG. 5. Comparison of IR Spectra of Eugenol (Blue) and the IR Spectrumof Gaseous Decomposition Products Derived from the Cured Cyanate Esterat 416° C.

In light of the TGA data, it was of interest to gain a qualitativeunderstanding of the decomposition mechanism for the cyanate ester. Thedecomposition was probed by means of an inline IR spectrometer coupledto a pyrolysis chamber. A gas phase spectrum captured at 416° C. showedevolution of phenolic compounds and isocyanic acid. The spectrum wasremarkably similar to that for eugenol (FIG. 5), suggesting thatdecomposition proceeds by cleavage of the aliphatic carbon bridge withconcomitant conversion of the cyanurate ring systems to isocyanic acid.The generation of eugenol and related phenols is particularlyinteresting from a sustainability perspective. In embodiments of theinvention thermoset materials can be effectively recycled by controlledpyrolysis. In embodiments the pyrolysis is conducted in a humid airenvironment. In embodiments the pyrolysis is conducted in an inert gaswith water present. In embodiments the products isolated from thepyrolysis are monophenols. In embodiments the products from thepyrolysis are bisphenols. In embodiments the products are a mixture ofmonophenols and bisphenols. Although the extent to which the o-methoxygroups contribute to the decomposition of these renewable resins isunclear, donation of electron density into the ring likely lowers thedecomposition temperature to a regime in which generation of phenolicproducts is favored over simpler decomposition products such as CO₂.

Sustainable phenols represent an important feedstock for new polymersand composite materials. Unlike petroleum sourced chemicals, naturallyderived products are often structurally diverse with this diversitysometimes affecting a variety of properties including thermal andoxidative stability. On a positive note, the functional groups presentin natural phenols can be an advantage, allowing for simplified,atom-economic synthetic procedures and imparting unique behavior toresins. In this context, the current invention shows that the renewablephenol eugenol is a viable candidate for the generation ofhigh-performance thermoset resins. Another unique aspect of theinvention is the ability to recycle eugenol-based thermoset resins via acontrolled pyrolysis process. This advance greatly improves thesustainability of these naturally derived resins.

In addition to cyanate esters, a wide variety of thermoset andthermoplastic materials can be synthesized from eugenol. Similar to theresults obtained for the cyanate ester, these materials have uniqueproperties due to the four-carbon aliphatic chain linking the aromaticrings together.

To expand the potential applications of this resin it became of interestto investigate blends of the cyanate ester with a thermoplastic that wasalso prepared from eugenol. In this manner a 100% bio-based compositematerial would be realized. Although cyanate esters have a number ofphysical properties that make them desirable in high performanceapplications, one of their drawbacks and thermoset materials in general,lies in their modest fracture resistance. Toughening approaches forthermosets date back to the late 1960s, where rubber was shown toimprove the fracture strength of epoxy resins. More recent studies haveexplored the use of reactive rubbers to improve the toughness of cyanateesters, esters, however, the use of these materials led to significantreductions in both the Tg and mechanical strength. In general,elastomeric modification has been shown to decrease elastic modulus,yield strength, and creep resistance. Furthermore, elastomermodification of highly crosslinked thermosets, such as cyanate esters,is not an effective approach since matrix yielding is the dominanttoughening mechanism. To mitigate these issues, the effects of blendingcyanate esters with various thermoplastic resins, includingpoly(ethylene phthalate), poly (ether imide), polysulfones, andpolycarbonates have been studied. In most cases the thermoplastic phaseseparates during cure of the cyanate ester with toughening of the bulkmaterial dependent on the resulting morphology. The morphology of thematerial is affected by the composition and molecular weight of thethermoplastic, cure temperature, kinetics, and pressure, among otherfactors.

The formation of a micro-sized particulate phase having a majoritycomposition of the modifying agent is widely considered to be the mosteffective morphology for imparting toughness to thermosets. However,this approach to toughening relies on reaction-induced phase separationwhich is sensitive to cure temperature. During the production ofcomposite parts from highly exothermic cure, significant temperaturegradients cannot be avoided and practical control of morphology isdifficult to achieve. In contrast, morphologies that allow alternativetoughening mechanisms and are not dependent on cure temperature may beuseful for composite part fabrication. For example, sub-micron phaseseparation that results in domains smaller than optical wavelengths oflight or interpenetrating networks have also been shown to provideaugmented fracture strength. In one study, polycarbonates blended withepoxy resins were shown to be completely miscible upon cure at loadingsof up to 12%. Homogenous formulations of this type had improved flexuralmodulus compared to related heterogeneous blends. Another study onphenoxy/epoxy blends showed that at high epoxy cure rates, homogeneousnetworks were produced that demonstrated higher fracture toughnesscompared to heterogeneous morphologies, at some expense to blend Tg.This effect has also been observed with polycarbonate/cyanate esterblends. Loadings of up to 50% polycarbonate with cyanate esters havebeen shown to form single phase interpenetrating networks with improvedtoughness. There are two keys to achieving this morphology. First, themodifying polymer's structure should closely match that of its intendedthermoset host. Second, the molecular weight of the thermoplastic shouldbe kept relatively low, both to generate a homogenous network and tolimit viscosity increases, thus having minimal effects on fiberreinforced composite processing.

Polycarbonates (EPC) were prepared by reaction of the bisphenol withtriphosgene in pyridine at room temperature. The product was isolated asa white solid by precipitation in water followed by a methanol wash andreprecipitation.

The miscibility of EPC and the cyanate ester along with the curebehavior and morphology of the blend was evaluated by Small Angle LaserLight Scattering (SALLS). The overall scattering intensity as a functionof film temperature was integrated. 20% polycarbonate does not inhibitcyanate ester crystallization as evidenced by the relatively highscattering intensity at room temperature. Cross-polarized microscopyconfirmed the crystallinity of the film. A significant decrease in theintensity of the scattered light was observed at the melting point ofthe cyanate ester resin which was depressed by nearly 20 degreescompared to the pure resin. After this initial drop in intensity, nofurther change in scattering intensity was observed either during orafter the cure of the cyanate ester. The lack of a significant increasein the intensity of scattered light indicates that no phase separationoccurred at length scales comparable to the wavelength of the incidentlight. To provide further evidence, a DSC experiment was conducted withthe blended material. The DSC scan showed the initial glass transitiontemperature of the polycarbonate and the melting transition of thecyanate ester, as well as complete cure on heating to 350° C. Oncompletion of cure and a second scan to establish a baseline, the DSCsample was removed from its container, examined, and found to beoptically clear. Although a distinct glass transition temperature wasnot observed after complete cure, as is sometimes the case forthermosetting network polymers, the combination of DSC and SALLS dataclearly indicate that no phase separation takes place during cure.

To further characterize the cure behavior of the blend, an 80:20(cyanate ester:polycarbonate) blend was cured and then evaluated by TMA.As expected based on the SALLS and DSC data, only one T_(g) was observedat 132° C. (tan δ) compared to the T_(g) of the pure cyanate ester (186°C.-tan δ) and that of the polycarbonate (71° C.-DSC). This value issimilar to that predicted from the Fox relation (140.5° C.) in which theK-parameter is estimated as T_(g1)/T_(g2) in the Gordon-Taylor equation.The presence of only one distinct T_(g) provides additional support forthe existence of a homogenous network.

To investigate the lack of phase separation during cure, an end-groupanalysis of the polycarbonate was conducted. The synthesis of thepolycarbonate should yield phenolic end-groups which may react withcyanate esters to give imidocarbonate linkages. To quantify the amountof residual phenolic end-groups, the polycarbonate was allowed to reactwith TBDMSCl in pyridine/triethylamine and was then worked up byprecipitation in methanol. ¹H NMR spectroscopy of the product revealedincorporation of TBDMS in the product. By comparing the integrals fromthe methoxy groups to those of the tert-butyl group on the endcaps, amolecular weight of 9575 daltons was calculated. This agrees reasonablywell with the GPC results (M_(n)=8360) and may be higher due to thereprecipitation steps which would be expected to reduce the amount oflighter oligomers. To determine if any chemical grafting was takingplace during the cure reaction, a mixture of the polycarbonate and thecyanate ester were cured to form a homogenous puck. The puck was thenrepeatedly extracted with warm CH₂Cl₂ and after evaporation, the extractwas weighed. In the extraction experiment, 160 mg of the cyanate esterand 38 mg of the polycarbonate were used. After extraction, the totalmass accounted for in both fractions was 195 mg or 98.5% recovery. Themass of the polycarbonate extract was 42 mg, while the residual curedcyanate ester weighed 153 mg. The ease of extraction and essentiallyquantitative recovery of the polycarbonate proves that no significantreaction between polycarbonate end-groups and the cyanate ester resinoccur. Instead the relatively low molecular weight of the polycarbonateallows for the formation of a homogenous system without covalentbonding. The relatively low molecular weight of the polymer and theflexible 4-carbon chain between aromatic rings are likely importantstructural characteristics for the formation of the homogenous network.

EXPERIMENTAL SECTION

General:

Eugenol, Grubbs' first generation catalyst, cyanogen bromide andtriethylamine were purchased from Sigma Aldrich and used as received.Anhydrous ether was obtained from Fischer Scientific and used asreceived. NMR spectra were collected on a Bruker Avance II 300 MHz NMRspectrometer. Samples were prepared in CDCl₃ and spectra were referencedto the solvent peaks (δ=7.26 and 77.16 ppm for ¹H and ¹³C spectra,respectively). Fourier Transform Infrared Spectroscopy (FT-IR) wascarried out using a Thermo Nicolet Nexus 6700 FTIR equipped with theSmart iTr attenuated total internal reflection (ATR) accessory, singlebounce diamond crystal. The detector type was a liquid nitrogen cooledMCTA. FTIR spectra are an average of 32 scans, at 4 cm⁻¹ resolution, andhave been baseline and background corrected. Elemental analysis wasperformed by Atlantic Microlabs Inc. Norcross, Ga.

Example 1 (E/Z)-4,4′-(but-2-ene-1,4-diyl)bis(2-methoxyphenol) (1)

Eugenol (25.88 g, 158 mmol) was combined with Grubbs' first generationcatalyst (0.532 g, 0.4 mol %) under a nitrogen atmosphere to form athick purple solution. Immediate evolution of ethylene was observed. Theflask was then placed under reduced pressure (20 Torr) for 48 hours withstirring to yield a thick resinous mass. The resulting solid wasdissolved in 1 liter of 1 M NaOH and filtered through a celite pad toremove a dark black precipitate. After filtration, the solution wasacidified with concentrated HCl which resulted in the precipitation of apale gray solid. The solid was collected by filtration, washed withwater and air-dried overnight. The solid was then dissolved in CH₂Cl₂,washed with water, and the organic layer dried over MgSO₄. The solventwas then removed in vacuo to yield 22.24 g of product (93% yield).

Example 2 4,4′-(butane-1,4-diyl)bis(2-methoxyphenol) (2)

1 (22.24 g, 74.1 mmol) was dissolved in 150 mL of anhydrous ethanol. Thesolution was transferred to a glass bomb and 0.5 g of 10° % Pd/C wasadded. The mixture was shaken under 40-50 psi hydrogen for 3 h. Theproduct mixture was filtered through celite and the solvent removed invacuo to yield a thick oil in nearly quantitative yield.Recrystallization from hot ethanol/water or ethanol/ether solutionsprovided analytically pure material. Higher purity material was obtainedby vacuum sublimation. ¹H NMR (CDCl₃) δ 6.90-6.82 (m, 2H, Ph), 6.73-6.65(m, 4H, Ph), 5.61 (bs, 2H, Ph-OH), 3.89 (s, 6H, —OMe), 2.66-2.53 (m, 4H,—CH2), 1.72-1.61 (m, 4H, —CH2). ¹³C NMR (CDCl₃) δ 146.5 (2C, Ph), 143.7(2C, Ph), 134.7 (2C, Ph), 121.1 (2C, Ph), 114.3 (2C, Ph), 111.18 (2C,Ph), 56.0 (2C, —OMe), 35.6 (2C, —CH₂), 31.4 (2C, —CH₂). Anal. Calcd forC₁₈H₂₂O₄: C, 71.50; H, 7.33. Found: C, 71.80; H, 7.47.

Example 3 1,4-bis(4-cyanato-3-methoxyphenyl)butane (3)

2 (3.33 g, 11.0 mmol) was dissolved in 40 mL ether and 10 mL acetone.The flask was cooled to −50° C. and CNBr (3.02 g, 28.5 mmol) was addedas a solid. Triethylamine (2.54 g, 25.1 mmol) was then added dropwiseand the mixture was allowed to slowly warm up to 10° C. over the courseof 1.5 h. The resulting white precipitate was collected on a frit andwashed with 2×30 mL ether, 5×30 mL water, and finally 2×20 mL ether. Theremaining solid was then dissolved in ethyl acetate, filtered, driedover MgSO₄, and refiltered to give a pale yellow solution. Removal ofthe solvent under reduced pressure gave 1.61 g of off-white solid. Theorganic washings were then combined, 30 mL ethyl acetate was added, andthe mixture was washed with water and the aqueous layer extracted withethyl acetate. The organic layers were combined, dried over MgSO₄, andthe solvent removed under reduced pressure to give 2.71 g of a paleyellow oil. 20 mL of ether was added and the flask was cooled to −20° C.to give an additional 1.21 g of product (73% yield). Analytically purematerial was obtained by recrystallization from warm ethyl acetate. ¹HNMR (CDCl₃) δ: 7.26 (d, J=8.3 Hz, 2H, Ph), 6.81-6.74 (m, 4H, Ph), 3.90(s, 6H, —OMe), 2.70-2.58 (m, 4H, —CH₂), 1.70-1.60 (m, 4H, —CH₂). ¹³C NMR(CDCl₃) δ: 148.5 (2C, Ph), 142.9 (2C, Ph), 140.5 (2C, Ph), 120.6 (2C,Ph), 117.0 (2C, Ph), 113.6 (2C, Ph), 109.8 (2C, —OCN), 56.3 (2C, —OMe),35.7 (2C, —CH₂), 31.0 (2C, —CH₂). Anal. Calcd for C₂₀H₂₀N₂O₄: C, 68.17;H, 5.72; N, 7.95. Found: C, 68.21; H, 5.88; N, 7.78.

Example 4

Polycarbonate synthesis. In a typical synthesis 1 (1.006 g, 3.3 mmol)was dissolved in 8 mL pyridine and the solution cooled to −20° C. withstirring. Triphosgene (0.384 g, 1.3 mmol) was added and the solution wasallowed to warm to room temperature. An additional 4 mL of pyridine wasthen added to dissolve residual solids. Stirring overnight yielded athick gray mixture which was poured into 200 mL of water to give a whiteprecipitate. The aqueous supernatant was decanted and replaced withmethanol. The mixture was heated to ˜50° C. and the solid was dispersedwith vigorous stirring for 30 minutes in the methanol solution. Thesupernatant was decanted off and the solid was dried first under astream of nitrogen and then in a vacuum oven at 50° C. overnight toyield 0.622 g (57%) of an off-white powder. The polymer was furtherpurified by dissolving in a minimum amount of methylene chloridefollowed by reprecipitation in methanol. 1H NMR (CDCl₃) δ 7.12 (d, J=8.0Hz, 2H, Ph), 6.80-6.70 (m, 4H, Ph), 3.87 (s, 6H, OMe), 2.63 (bs, 4H,CH₂), 1.67 (bs, 4H, CH₂)

Example 5

Polycarbonate endcapping. This procedure was conducted as described inthe literature. 100 mg of polycarbonate was dissolved in 6 mL ofpyridine. t-Butyldimethylsilyl chloride (0.468 g, 3.1 mmol) wasdissolved in triethylamine (1 mL) and this solution was then added tothe pyridine solution. The reaction was stirred under nitrogen at 50° C.for 24 h. The solvent was removed under reduced pressure to yield aresinous solid. The solid was then dissolved in a minimum ofdichloromethane and precipitated in methanol. After a furtherreprecipitation, the resulting solid was collected, washed withmethanol, and dried in a vacuum oven. The molecular weight of theendcapped polymer was determined by comparing the 1H NMR integrals forthe tert-butyl group from the endcap to the methoxy group from therepeat unit. The Mn calculated by this method was 9575 daltons.

Example 6

Solvent extraction of cyanate ester/polycarbonate network. An intimatemixture of 160 mg of 2 and 38 mg of the polycarbonate were added to acircular silicone mold with a diameter of 20 mm and a depth of 2 mm. Themold was heated to 150° C. under a slow flow of nitrogen and then heldat that temperature for 30 min. All of the solids melted to form aclear, homogeneous mixture. The temperature was then increased 10° C.every 10 minutes until it reached 210° C. and was then held at thattemperature for 24 h. After cooling to room temperature, the puck wasremoved from the mold, broken into several large pieces, and thentransferred to a glass vial. 5 mL of dichloromethane was added to thevial and the sample was gently heated to 35° C. for 15 minutes. Thedichloromethane solution was then decanted and any loose pieces ofmaterial were collected on a frit. The dichloromethane extraction wasrepeated 5 times and then the glass vial and frit were placed in avacuum oven to dry. The dichloromethane aliquots were combined and thesolvent removed under reduced pressure to leave a yellow residue. Afterdrying, the insoluble fragments of the puck weighed a total of 153 mg.The soluble residue from the dichloromethane fractions weighed 42 mg. Atotal of 195 mg of sample (98.5%) were accounted for in the experiment.

X-Ray Diffraction Studies.

X-ray intensity data were collected for omega scans at 296K on a BrukerSMART APEX II diffractometer with graphite-monochromated Mo Kα radiation(λ=0.71073 Å). Frames were integrated using the Bruker SAINT softwarepackage with a narrow-frame integration algorithm. Data were correctedfor absorption using the empirical multi-scan method (SADABS), and thestructures solved by direct methods using SHELXTL and refined byfull-matrix least squares refinement on F2. X-ray data for compounds 1and 2 have been deposited in the Cambridge Structural Database. (Acombined .cif file is included in the supporting information. Compounds2 and 3 have been deposited in the Cambridge Structural Database as CCDC942320 and CCDC 942319, respectively)

TGA/FTIR Analysis.

Samples were analyzed using a Thermo Nicolet Nexuus 6700 FTIR interfacedvia a heated gas cell and transfer line (held at 150° C. under N₂) to aTA instruments Q50 TGA. The TGA was set to ramp from room temperature to450° C. at a rate of 10 degrees per minute. FTIR spectra were collectedevery 30 s.

Preparation of Resin Pucks.

Cured polycyanurate samples were prepared by heating the dicyanate esterin a 6 mL glass vial to a temperature just above the melting point ofthe monomer. Once in the liquid state, the material was degassed at 300mm Hg for 30 minutes and then poured into silicone molds made fromR2364A silicone from Silpak Inc. (mixed at 10:1 by weight with R2364Bplatinum-based curing agent, degassed for 60 minutes at 25° C. and curedovernight at room temperature, followed by post-cure at 150° C. for 1hour). The open mold and sample were then placed in an oven at 25° C.under flowing nitrogen and cured following a cure protocol of 150° C.for 1 hour and 210° C. for 24 hours using a ramp rate of 5° C./min.Void-free discs measuring approximately 11.5-13.5 mm in diameter by 1-3mm thick and weighing 200-400 mg were obtained by this method. The discswere used for thermomechanical analysis (TMA) and hot water exposuretests.

Thermal Characterization.

DSC was performed on a TA Instruments Q200 calorimeter under 50 mL/min.of flowing nitrogen. Samples were subjected to a heat-cool-heat cyclefrom 40° C. to 350° C. with a ramp rate of 10° C./min. Oscillatory TMAwas conducted with a TA Instruments Q400 series analyzer under 50 mL/minof nitrogen flow. The discs were held in place via a 0.2 N initialcompressive force with the standard ˜5 mm diameter flat cylindricalprobe while the probe force was modulated at 0.05 Hz over an amplitudeof 0.1 N (with a mean compressive force of 0.1 N). Thermal lag wasdetermined as described previously.² To determine T_(g), the temperaturewas then ramped to 350° C., cooled to 100° C. and ramped again to 350°C., all at 50° C./min. Discs that were exposed to water were ramped from40° C. to 350° C., cycled between 100° C. and 200° C. to determinethermal lag and ramped again to 350° C./min, all at 20° C./min.Thermogravimetric analysis (TGA) (without FT-IR) was performed on a TAInstruments Q5000 analyzer with either nitrogen or air flow of 25mL/min. The samples were heated from ambient to 600° C. at 10° C./min.

Moisture uptake experiments were performed using cured discs of uniform11.7 mm diameter and 3 mm thickness. Each disk was placed into ˜300 mLof deionized water maintained at a temperature of 85° C. for 96 hours.The discs were then removed from the water, gently patted dry with apaper towel, and weighed a minimum of three times (all weights agreed towithin 0.0005 g) and then tested via oscillatory TMA to measure “wet”glass transition temperatures.

Embodiments of the invention generally refer to methods formanufacturing thermoplastics or resins from phenol including, isolatingeugenol synthetically or from at least one renewable resource, reactingthe eugenol with at least one metathesis catalyst to form an unsaturatedbisphenol, converting the saturated bisphenol to a resin or athermoplastic polymer, purifying the resins or thermoplastic polymers,and combining and curing the resins or thermoplastic polymers orresins/thermoplastic polymers with support material to produce compositematerials of thermoplastic polymers, resins, or blends of thermoplasticpolymers and resins. Embodiments further include hydrogenating theunsaturated bisphenol with at least one hydrogenating catalyst (under aH₂ environment) to yield a saturated bisphenol. In embodiments, thesaturated bisphenol is converted to a cyanate ester and further includescombining and curing the resins or thermoplastic polymers with supportmaterial to produce composite materials having a low water uptake ofless than 1.8% and glass transition temperature greater than 186° C.

Another aspect of the invention generally relates to methods formanufacturing thermoplastics or resins from bisphenol including,isolating eugenol synthetically or from at least one renewable resource,reacting the eugenol with at least one metathesis catalyst to form anunsaturated bisphenol, converting the unsaturated bisphenol to athermosetting resin or a thermoplastic polymer, or first hydrogenatingsaid unsaturated bisphenol to produce a saturated bisphenol and thenconverting said saturated bisphenol to a thermosetting resin orthermoplastic polymer, purifying the thermosetting resins orthermoplastic polymers, combining and curing the thermosetting resins orthermoplastic polymers or thermosetting resins and thermoplasticpolymers with support material to produce composite materials ofthermoplastic polymers, resins, or blends of thermoplastic polymers andthermosetting resins, and the composite materials are recycled back toeugenol via a controlled pyrolysis process.

Embodiments include converting the saturated bisphenol to a resin, wherethe resin is cyanate esters and/or epoxy resins. In embodiments, themetathesis catalyst is a homogeneous and/or heterogeneous catalyst.Embodiments further include separating the heterogeneous catalyst byfiltration. Other embodiments further include separating the homogeneouscatalyst by extraction of the bisphenol into water with a base andreprecipitation of the bisphenol with at least one acid. Embodimentsfurther include using at least one solvent under pressure of about0.1-100 atm and with at least one catalyst. In embodiments, at least onesolvent is selected from the group consisting of alcohol/THF and thecatalyst is selected from the group consisting of Ni, Rd, Pt, Ru, Cu,and any combination thereof. In embodiments, the homogeneous catalystsare selected from the group consisting of Ru, Re, Mo, W based olefinmetathesis catalysts, and any combination thereof. In embodiments, theheterogeneous catalysts are selected from the group consisting of Ru,Re, Mo, W based olefin metathesis catalysts on inorganic or polymersupports, and any combination thereof.

In embodiments, the resins are selected from the group consisting ofcyanate esters, epoxy resins, benzoxazines, and any combination thereof.In embodiments, the thermoplastic polymers are selected from the groupconsisting of polycarbonates prepared with reagents including phosgene,triphosgene, diphenylcarbonate, other carbonates, and any combinationthereof. In embodiments, the support material is selected from the groupconsisting of carbon fiber, carbon nanotubes, graphene, glass fibers,metal oxides, clay, nanofibers and any combination thereof and nanotubesor other support material made of materials selected from the groupconsisting of glass, carbon, and any combination thereof. Inembodiments, the curing temperature for resins being dicyanate estersare from about 50° C. to about 350° C.

In embodiments, the thermoplastic polymers are used directly ormelt-pressed with said support fibers to yield composite materials ortougheners for thermoset resins. In embodiments, a thermosetting resinand the thermoplastic resin prepared from eugenol are thermally cured togenerate a homogenous network. In embodiments, the pyrolysis process isat a temperature range of about 250° C. to about 450° C. In embodiments,the pyrolysis process is in the presence of a hydrolysis catalyst. Inembodiments, the recycled phenols or bisphenols are purified bydistillation, sublimation, crystallization, or column chromatography.

PROPHETIC EXAMPLES

Prophetic examples are for illustration purposes only and not to be usedto limit any of the embodiments.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassedwithin the invention. The upper and lower limits of these smaller rangesmay independently be included or excluded in the range, and each rangewhere either, neither or both limits are included in the smaller rangesis also encompassed within the invention, subject to any specificallyexcluded limit in the stated range. Where the stated range includes oneor both of the limits, ranges excluding either or both of those includedlimits are also included in the invention.

While the invention has been described, disclosed, illustrated and shownin various terms of certain embodiments or modifications which it haspresumed in practice, the scope of the invention is not intended to be,nor should it be deemed to be, limited thereby and such othermodifications or embodiments as may be suggested by the teachings hereinare particularly reserved especially as they fall within the breadth andscope of the claims here appended.

What is claimed is:
 1. A method for manufacturing thermoplastics orresins from a bisphenol, comprising: isolating eugenol synthetically orfrom at least one renewable resource; reacting said eugenol with atleast one metathesis catalyst to form an unsaturated bisphenol;converting said unsaturated bisphenol to a thermosetting resin or athermoplastic polymer; or first hydrogenating said unsaturated bisphenolto produce a saturated bisphenol and then converting said saturatedbisphenol to a resin or thermoplastic polymer; purifying said resins orthermoplastic polymers; and combining and curing said resins orthermoplastic polymers or resins and thermoplastic polymers with supportmaterial to produce composite materials of thermoplastic polymers,resins, or blends of thermoplastic polymers and resins.
 2. The methodaccording to claim 1, further comprising hydrogenating said unsaturatedbisphenol with at least one hydrogenating catalyst under a H₂environment to yield a saturated bisphenol.
 3. The method according toclaim 1, wherein said resin is a cyanate ester and/or epoxy resins andfurther comprising combining and curing said resins or thermoplasticpolymers with support material to produce composite materials having alow water uptake of less than 1.8% and glass transition temperaturegreater than 186° C.
 4. The method according to claim 1, wherein saidresin is cyanate esters and/or epoxy resins.
 5. The method according toclaim 1, wherein said one metathesis catalyst is a homogeneous and/orheterogeneous catalyst.
 6. The method according to claim 5, furthercomprising separating said heterogeneous catalyst by filtration.
 7. Themethod according to claim 5, further comprising separating saidhomogeneous catalyst by extraction of said bisphenol into water with abase and reprecipitation of said bisphenol with at least one acid. 8.The method according to claim 5 further comprising using at least onesolvent under pressure of about 0.1-100 atm and with at least onecatalyst.
 9. The method according to claim 8, wherein said at least onesolvent is a mixture of alcohol and THF and said catalyst is selectedfrom the group consisting of Ni, Pd, Pt, Ru, Cu, and any combinationthereof.
 10. The method according to claim 5, wherein said homogeneouscatalysts are olefin metathesis catalysts based on Ru, Re, Mo, W, andany combination thereof.
 11. The method according to claim 5, whereinsaid heterogeneous catalysts are olefin metathesis catalysts oninorganic or polymer supports based on Ru, Re, Mo, W and any combinationthereof.
 12. The method according to claim 1, wherein said resins areselected from the group consisting of cyanate esters, epoxy resins,benzoxazines, and any combination thereof.
 13. The method according toclaim 1, wherein said thermoplastic polymers are selected from the groupconsisting of polycarbonates prepared with reagents includingpolysulfones, polyethers, poly ether ether ketones (PEEK), polyesters,alkylphenolics, polyarylates, and any combination thereof.
 14. Themethod according to claim 1, wherein said support material is selectedfrom the group consisting of carbon fiber, carbon nanotubes, graphene,glass fibers, metal oxides, clay, nanofibers, and any combinationthereof.
 15. The method according to claim 1, wherein said curingtemperature for resins ranges from about 50° C. to about 350° C. andsaid resins are dicyanate esters.
 16. The method according to claim 1,wherein said thermoplastic polymers are melt-pressed with said supportmaterials to yield composite materials or tougheners for thermosettingresins.
 17. The method according to claim 1, wherein a thermosettingresin and said thermoplastic resin prepared from eugenol are thermallycured to generate a homogenous network.
 18. A method for manufacturingthermoplastics or resins from phenol, comprising: isolating eugenolsynthetically or from at least one renewable resource; reacting saideugenol with at least one metathesis catalyst to form an unsaturatedbisphenol; converting said unsaturated bisphenol to a thermosettingresin or a thermoplastic polymer; or first hydrogenating saidunsaturated bisphenol to produce a saturated bisphenol and thenconverting said saturated bisphenol to a thermosetting resin orthermoplastic polymer; purifying said resins or thermoplastic polymers;and combining and curing said resins or thermoplastic polymers or resinsand thermoplastic polymers with support material to produce compositematerials of thermoplastic polymers, resins, or blends of thermoplasticpolymers and resins; and wherein said composite materials are recycledback to eugenol phenols and bisphenols via a controlled pyrolysisprocess.
 19. The method according to claim 18, further comprisinghydrogenating said unsaturated bisphenol with at least one hydrogenatingcatalyst under a H₂ environment to yield a saturated bisphenol.
 20. Themethod according to claim 18, wherein said resin is a cyanate esterand/or epoxies and further comprising combining and curing said resinsor thermoplastic polymers with support material to produce compositematerials having a low water uptake of less than 1.8% and glasstransition temperature greater than 186° C.
 21. The method according toclaim 18, wherein said pyrolysis process is at a temperature range ofabout 250° C. to about 450° C.
 22. The method according to claim 18,wherein said pyrolysis process is in the presence of a hydrolysiscatalyst.
 23. The method according to claim 18, wherein recycled saidphenols or bisphenols are purified by distillation, sublimation,crystallization, or column chromatography.